Vertical axis wind turbine

ABSTRACT

A vertical axis wind turbine (VAWT) with improved and optimized wind-directing, wind-shaping, and wind-power conversion features is disclosed. The shapes of these features directly affect the ability of the VAWT to use the power of moving air, such as wind, to spin a rotor and create torque on a rotor shaft to generate electricity. The wind-power-conversion mechanical efficiency of the invention is significantly improved over previous efforts, to the point that the invention can convert wind energy into electrical power at a price-to-performance ratio that competes with or surpasses existing alternative energy technologies.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of U.S. patent applicationSer. No. 15/193,659, filed 27 Jun. 2016, which in turn claims thebenefit of U.S. Provisional Patent Application 62/184,742, filed 25 Jun.2015, the entireties of both of which are incorporated herein byreference.

FIELD OF THE INVENTION

This disclosure relates to methods, devices, and systems directed toimproving wind directing, shaping, and power conversion, to createtorque on a rotor shaft to generate electricity.

BACKGROUND OF THE INVENTION

Although wind power has the potential to provide a large proportion ofthe world's electricity needs, the variability in the velocity of thewind often makes it an unreliable power source. In particular, thisvariability makes it difficult to construct wind-driven power-generatingdevices that are effective and efficient under all wind conditions. Byway of non-limiting example, the devices disclosed in U.S. Pat. No.3,942,909 to Yengst, U.S. Pat. No. 4,632,637 to Traudt, and U.S. Pat.No. 4,818,181 to Kodric concentrate low and moderate winds to producepower and are designed to fold or feather in high winds; while thesetechniques protect the structural integrity of the device, they alsodecrease the device's ability to produce power in high winds.

Conversely, by way of non-limiting example, the device disclosed in U.S.Pat. No. 5,391,926 to Staley et al. can harness high winds for powerproduction, but is not capable of generating adequate torque forcontinual, reliable power generation in low or moderate winds.

One offered solution for the problem of variable wind velocity has beenthe vertical axis wind turbine (VAWT). Unlike horizontal axis(propeller-type) windmills, VAWTs pivot about a long vertical axis, suchthat they may face directly into a wind. A VAWT, therefore, can harnesswind energy from large columns of air, making them practical for powergeneration in low and moderate winds. When combined with features thatallow a wind-driven power generator to operate robustly in high winds, aVAWT can be used to generate power in a wide range of wind conditions.By way of non-limiting example, one such device is disclosed in U.S.Pat. No. 6,538,340 to Elder. However, given their relative complexitycompared to horizontal axis windmills, VAWTs continue to suffer fromlower cost efficiency than other alternative energy technologies.

There is a long-felt need for VAWT devices with improved costefficiency, which preferably would provide continual, reliable powergeneration in all wind conditions at costs comparable to otheralternative energy generation methods, devices, and systems.

SUMMARY OF THE INVENTION

Certain embodiments include a vertical axis wind turbine, comprising atleast one rotor blade, turning a shaft; at least one rotor plate,attached to the at least one rotor blade at one or more of a top and abottom of the at least one rotor blade; a rotationally symmetric statorskirt, supporting the at least one rotor plate and comprising Nidentical trapezoidal panels, each trapezoidal panel forming an angle αrelative to a horizontal axis, the stator skirt having a horizontalcross-section of a regular polygon having N sides; at least one statorfin, each stator fin being attached at a bottom of the stator fin to thestator skirt and comprising a fin flip, the fin flip being forming anangle β relative to a longitudinal axis of the stator fin and adapted tocompress wind and direct the wind to the rotor blades in a predetermineddirection; and a top frame, attached to a top of each stator fin.

In some embodiments, the predetermined direction is clockwise. In otherembodiments, the predetermined direction is counterclockwise. In certainembodiments, the at least one rotor blade may comprise three rotorblades. In some of these embodiments, each of the three rotor blades isdisposed at an angle of 120° relative each of the other two rotorblades.

In certain embodiments, each of a leading vertical face and a trailingvertical face of each rotor blade may be semielliptical. In some ofthese embodiments, a distance between the leading vertical face and thetrailing vertical face may be greatest at a center of each face, suchthat the horizontal cross-section of the rotor blade is a crescent. Inother embodiments, a distance between the leading vertical face and thetrailing vertical face may be uniform, such that the horizontalcross-section of the rotor blade is of constant width.

In some embodiments, the at least one stator fin may comprise threestator fins. In other embodiments, the at least one stator fin maycomprise six stator fins.

In some embodiments, the at least one stator fin may be disposed in anarrangement that is rotationally symmetric about the shaft. By way ofnon-limiting example, the at least one stator fin may comprise threestator fins spaced 120° apart, or may comprise six stator fins spaced60° apart.

In some embodiments, β may be between about 15° and about 75°, morepreferably between about 30° and about 60°, and most preferably about45°.

In some embodiments, a length of each fin flip may be about 2 inches. Insome embodiments, N may be between 3 and 9, more preferably between 4and 8, and most preferably 6.

In some embodiments, α may be between about 12° and about 80°, morepreferably between about 24° and about 70°, and most preferably about36° or about 60°.

In some embodiments, the rotor blades may be separate components, eachattached to the at least one rotor plate but not attached to the otherrotor blades. In other embodiments, the rotor blades may beinterconnected to form a unitary rotor.

In some embodiments, the at least one rotor plate may comprise two ormore rotor plates, the two or more rotor plates being vertically stackedand independently moveable.

In some embodiments, at least one rotor plate may have at least one gapor hole to allow vertical air flow.

In certain embodiments, the vertical axis wind turbine may furthercomprise an amplifier skirt, disposed on a top of the vertical axis windturbine and attached to the top frame. The amplifier skirt may be, butneed not be, a “mirror image” of the stator skirt.

In some embodiments, the at least one rotor blade may have a diametergreater than a radius of the at least one rotor plate to which the atleast one rotor blade is attached.

Various embodiments of the present invention are directed to windturbine designs that employ both aerodynamic lift and drag forces, inconcert with back pressure relief, in a consolidated vertical-axis windturbine apparatus utilizing stator and rotor blades so as to provide anomni-directional vertical-axis wind turbine, having an increasedcapacity to convert wind energy to electrical energy. The stator bladesare designed, adapted and configured do reduce back pressure, whileproviding a means for effectively transferring torque to the rotorblades, which in certain embodiments, are designed as bidirectionalairfoils, and therefore, are conducive to the laminar conduction of windthrough or around the device. In preferred embodiments, oncoming windthat is oriented nearly perpendicular to the stator is shaped in adesired fashion to achieve channeling of the wind into the interior ofthe device so as to rotate the rotor by being directed (e.g. via theflip angle of the end of a stator) so as to achieve desired overalloperating efficiencies and to increase the wind directional aggregate ofthe device.

The shapes of blades employed can vary, but are preferably selected tobe conducive to the laminar flow of wind through the device, with statorand bade configurations selected to maximize the induced torquepotential and to improve attack angles. The stator/rotor combination istherefore selected to be effective for increasing both wind speed andpressure, by means of the conservation of angular momentum.

In certain embodiments, the device is devoid of a rounded, symmetricalbase unit (or top unit), with some such designs instead employingparticular linear surfaces in a manner to direct incoming wind toeffectively achieve desired attack angles to the rotor so as to maximizeefficiencies. Certain embodiments include a housing that includes a topcoupled to a bottom via one or more optional supports, which may includestator elements. The housing may include surfaces adapted to direct windfrom outside the housing to inside the housing toward the rotor. Whilethe housing may be surrounded by a net or screen, preferred embodimentseliminate the same. In other embodiments, a top structure is providedthat is generally symmetrical and the mirror image of the base unit,such that the same linear surfaces are designed to funnel and direct andshape the wind into the interior of the device. While the top-mostsurface of the top of the device may be curved to direct water oroutside air as desired, in other embodiments the top surface isrelatively flat so as to accommodate the stacking of at least two unitsatop each other. In such a manner, a user can decide to stack units toachieve higher vertical structures, with wind energy generation possibleat each level, thus adding some redundancy to the overall system, andalso providing the ability to slightly change the internal and workingcomponents of the individual units to adjust for differences in windconditions. For example, different sized and shaped rotors or statorscan be employed with two stacked units, thus facilitating some varietyof performance between the two units in any given wind conditionexperienced. In some stacked configurations, the air from one unit maybe directed advantageously into the other unit.

Various embodiments of the present invention include a plurality of windturbine diffusers to increase the velocity of the air entering theturbine's rotor plane, thus increasing the power output and efficiencyby having air being accelerated over the turbine rotor blades.

In certain embodiments a static diffuser about a horizontal axis, butrotatable about the vertical axis, may be employed, and in still otherembodiments, the diffuser further comprises one or more vent structureslocated on the exterior surface.

In aspects of the present disclosure, a vertical axis wind turbinecomprises at least one rotor blade, turning a shaft; a rotationallysymmetric stator skirt, wherein at least a portion of a wind-facingsurface of the stator skirt is parabolic, and wherein the stator skirthas a horizontal cross-section of an ellipse; and at least one statorfin, each stator fin being attached at a bottom of the stator fin to thestator skirt and comprising a fin flip, the fin flip being disposed atan angle of β relative to a longitudinal axis of the stator fin andadapted to compress wind and direct the wind to the rotor blades in apredetermined direction.

In embodiments, the predetermined direction may be counterclockwise. Inembodiments, the at least one rotor blade may comprise three rotorblades. In embodiments, at least one of a leading vertical face and atrailing vertical face of each rotor blade may be arcuate or parabolic.In embodiments, the at least one stator fin may comprise three statorfins.

In embodiments, the wind-facing surface of the stator skirt may comprisea lower conical portion and an upper parabolic portion.

In embodiments, an angle α between the wind-facing surface of the statorskirt and a horizontal axis, as measured by an average or at any pointof the stator skirt, may be less than about 45° or more than about 55°.The angle α may, but need not, be between about 35° and about 40° orbetween about 55° and about 65°.

In embodiments, the ellipse may be a circle. In embodiments, thevertical axis wind turbine may have a height-to-width ratio of betweenabout 0.1 and about 3.0.

In aspects of the present disclosure, a vertical axis wind turbinecomprises at least one rotor blade, turning a shaft; a rotationallysymmetric stator skirt, wherein at least a portion of a wind-facingsurface of the stator skirt is parabolic, and wherein the stator skirthas a horizontal cross-section of an ellipse; a rotationally symmetricamplifier skirt, wherein at least a portion of a wind-facing surface ofthe amplifier skirt is parabolic, and wherein the amplifier skirt has ahorizontal cross-section of an ellipse; and at least one stator fin,each stator fin being attached at a bottom of the stator fin to thestator skirt and comprising a fin flip, the fin flip being disposed atan angle of β relative to a longitudinal axis of the stator fin andadapted to compress wind and direct the wind to the rotor blades in apredetermined direction.

In embodiments, at least one of a leading vertical face and a trailingvertical face of each rotor blade may be arcuate or parabolic. Inembodiments, the wind-facing surface of the amplifier skirt may comprisean upper conical section and a lower parabolic section.

In embodiments, at least one of the ellipse of the stator skirt and theellipse of the amplifier skirt may be a circle.

In embodiments, the vertical axis wind turbine may have aheight-to-width ratio of between about 0.1 and about 3.0.

In aspects of the present disclosure, a vertical axis wind turbinecomprises at least one rotor blade turning a shaft; at least one rotorplate attached to the at least one rotor blade at one or both of a topand a bottom of the at least one rotor blade; a rotationally symmetricstator skirt, supporting the at least one rotor plate and comprising Nidentical trapezoidal panels, each trapezoidal panel forming an angle αwith respect to a horizontal axis, the stator skirt having a horizontalcross-section of a regular polygon having N sides; at least one statorfin, each stator fin being attached at a bottom of the stator fin to thestator skirt and comprising a fin flip, the fin flip being disposed atan angle of β relative to a longitudinal axis of the stator fin andadapted to compress wind and direct the wind to the rotor blades in apredetermined direction; and a top frame, attached to a top of eachstator fin, wherein α is less than about 45° or more than about 55°.

In embodiments, the predetermined direction may be counterclockwise.

In embodiments, the at least one rotor blade may comprise three rotorblades.

In embodiments, each of a leading vertical face and a trailing verticalface of each rotor blade may be semielliptical.

In embodiments, the at least one stator fin may comprise three statorfins.

The present invention generally comprises a wind turbine that permits alarge fraction of the energy of incident wind to be converted to usefulwork. The unique construction of the wind turbine thus yields a moreefficient wind turbine that is adaptable to many uses, including notonly energy generation form wind, but from water in tidal applications.

While specific embodiments and applications of the present inventionhave been illustrated and described, it is to be understood that theinvention is not limited to the precise configuration and componentsdisclosed herein. Various modifications, changes, and variations whichwill be apparent to those skilled in the art may be made in thearrangement, operation, and details of the methods and systems of thepresent invention disclosed herein without departing from the spirit andscope of the invention. It is important, therefore, that the claims beregarded as including any such equivalent construction insofar as theydo not depart from the spirit and scope of the present invention.

The advantages of the present invention will be apparent from thedisclosure contained herein.

For purposes of further disclosure and to comply with applicable writtendescription and enablement requirements, the following referencesgenerally relate to methods, devices, and systems directed to improvingwind directing, shaping, and power conversion, to create torque on arotor shaft to generate electricity, and related methods, devices, andsystems, and are hereby incorporated by reference in their entireties:

U.S. Pat. No. 3,942,909, entitled “Vertical axis fluid driven rotor,”issued 9 Mar. 1976 to Yengst (“Yengst”). Yengst describes a verticalaxis rotor comprising curved vanes overlapping in their diameters andattached to a shaft, a pair of spaced-apart end plates adapted to holdand permit rotation of the shaft to which the vanes are attached, andmeans for weighting an edge of the vanes comprising a plurality oftubes, each tube being positioned along the outer edge of each vane andconnected to a source of liquid so that as the shaft and vanes rotate,fluid rises in the tubes.

U.S. Pat. No. 4,632,637, entitled “Wind turbine,” issued 30 Dec. 1986 toTraudt (“Traudt”). Traudt describes a wind turbine device having a mainrotatable driven shaft, a plurality of elongated blades operativelymounted on the main shaft for unitary rotation with the main shaft, theblade extending substantially radially away from the main shaft andadapted to fold downwind under naturally occurring forces andsimultaneously feather in direct response to the folding movement, andmeans associated with the blades for increasing the rate of foldrelative to the rate of feather as the speed of rotation increases.

U.S. Pat. No. 4,818,181, entitled “Wind turbine,” issued 4 Apr. 1989 toKodric (“Kodric”). Kodric describes a wind turbine comprising a housingpivotally positioned atop a support structure; a hub rotatablypositioned at one end of the housing; at least two arm members, attachedto and radiating outwardly from the hub and being spaced equally fromone another, each having an identical structure comprising an inner armportion and an outer arm portion at an angle of from 75° to 105° to theinner portion, the arm members being oriented in the same substantiallyvertical plane; a vane pivotally attached to each outer arm portion;means for biasing the pitch angle of each vane about its outer armportion to catch the wind and thereby impart rotation to the hub; andmeans for orienting the housing so that the vanes may catch the wind.

U.S. Pat. No. 5,391,926, entitled “Wind turbine particularly suited forhigh-wind conditions,” issued 21 Feb. 1995 to Staley et al. (“Staley”).Staley describes double-curved, stationary stators for more effectivelydirecting currents into a rotor assembly to impart a higher rotationalvelocity and greater torque upon the turbine shaft. In addition, thestationary stators provide a structural integrity necessary foroperation during high-wind conditions. This aspect also prevents thedisruption of rotation by shielding the rotors from windscounter-directional to their rotation which may occur as the windshifts.

U.S. Pat. No. 6,172,429, entitled “Hybrid energy recovery system,”issued 9 Jan. 2001 to Russell (“Russell”). Russell describes doublespeed Savonius rotor electrical generating apparatuses, each of whichincludes two Savonius type rotors mounted adjacent to one another forrotation about a common axis with the blades of the rotor units beingarranged so that the rotor units rotate in opposite directions relativeto one another under the influence of a given wind or flow of water.

U.S. Pat. No. 6,538,340, entitled “Wind turbine system,” issued 25 Mar.2003 to Elder (“Elder”). Elder describes an improved lightweightvertically rotating wind turbine having enhanced conversion of windkinetic energy into usable energy, comprising a wind-collecting basewith a bottom surface defining an area and a top surface defining anarea, wherein the area of the bottom surface is larger than the area ofthe top surface, the top surface comprises an energy-transfer element,and the wind-collecting base comprises an upward tapered base having anangle to smoothly direct wind currents; a vertically rotating shaft witha top end and a bottom end, wherein the bottom end is mechanicallyconnected to the energy-transfer element; an energy-utilizing deviceresponsive to the shaft through the energy-transfer element of the topsurface of the base; a top plate attached in the vicinity of the top endof the vertically rotating shaft; a bottom plate that defines a diameterand is attached to the vertically rotating shaft at a location above thetop surface of the base; a plurality of vertically oriented torquegenerating elements having outer edges and inner edges which are locatedcircumferentially around the vertically rotating shaft between the topplate and the bottom plate and are attached to the round top plate andthe round bottom plate at their ends to form a cage assembly; aplurality of vertically oriented flat wind directing elements arrangedcircumferentially around the cage assembly and adjacent to the outeredges of the vertically oriented flat torque generating elements; anopen cover comprising concentric braces comprising two side bearings;and a top shield having a central pivoting point and an outer terminusabove the side bearings of the open cover, wherein the wind turbineelements are constructed from lightweight materials which allow theenhanced conversion of wind kinetic energy into mechanical energy by thewind turbine.

U.S. Pat. No. 6,638,005, entitled “Coaxial wind turbine apparatus havinga closeable air inlet opening,” issued 28 Oct. 2003 to Holter et al.(“Holter”). Holter describes a coaxial wind turbine apparatus includinga pair of rearward-mounted, spring-loaded fins to orient the air inletopening to face the direction of the oncoming wind and close a damperpanel or shutter array at the air inlet opening during very high windconditions.

U.S. Pat. No. 6,740,989, entitled “Vertical axis wind turbine,” issued25 May 2004 to Rowe (“Rowe”). Rowe describes a vertical axis windturbine comprising a turbine rotor with rotor blades disposed forrotation about a substantially vertical axis; and a plurality ofvertically extending stator vanes circumferentially spaced apart aboutthe rotor in an annular array, each vane having a radially inward facingsurface, a radially outward facing surface, and a flange on an outeredge of each vane. U.S. Pat. No. 6,984,899, entitled “Wind dam electricgenerator and method,” issued 10 Jan. 2006 to Rice (“Rice”). Ricedescribes a wind generator for generating electricity in response towind flow, comprising a windmill comprising a shaft; a plurality ofblades secured to the shaft; at least two moveable air foils which forman adjustable size opening for directing a selectable amount of windflow into the plurality of blades; a base supporting the at least twoair foils, the base being rotatably mounted for orienting the at leasttwo air foils into the wind flow; a ring gear mechanically affixed tothe shaft; and a plurality of generators arranged for mechanicalinterconnection with the ring gear.

U.S. Pat. No. 7,329,965, entitled “Aerodynamic-hybrid vertical-axis windturbine,” issued 12 Feb. 2008 to Roberts et al. (“Roberts”). Robertsdescribes a vertical axis wind turbine which includes a rotor airfoiland stator blade combination. The rotor airfoils have a horizontalcross-section with a crescent shape including a convex leading side anda concave trailing side with a thicker middle section that tapers tonarrower sections at ends. The stator blades have a horizontalcross-section with a planar side and a convex side. Rotor airfoil andstator blade combinations are secured between upper and lower annularsails.

U.S. Pat. No. 7,347,660, entitled “Cross-flow wind turbine,” issued 25Mar. 2008 to Taylor et al. (“Taylor”). Taylor describes cross-windturbines wherein an airfoil stator causes wind to accelerate along itssurface and creates a low pressure area on the leading face of the rotorblade during the power stroke. A blocking stator blocks wind fromimpeding the movement of the rotor blades during the return cycle anddirects wind onto the trailing face of the rotor blades during the powercycle. A large pressure differential is created between the leading faceof the rotor blade and the trailing face of the rotor blade during thepower cycle which creates a large amount of force that rotates the rotorblade about the central shaft.

U.S. Pat. No. 7,573,148, entitled “Boundary layer wind turbine,” issued11 Aug. 2009 to Nica (“Nica”). Nica describes a wind turbine comprisinga stator assembly having a plurality of stator blades for tangentiallyredirecting wind into an enclosure formed by the stator blades; and arotor assembly positioned within the enclosure formed by the statorblades, the rotor assembly having a plurality of stacked disks connectedto a shaft means, the stacked disks being closely spaced from each otherso as to create, in use, a boundary layer effect on surfaces of thedisks that contributes in rotating the disks, each disk having aplurality of rotor blades disposed on an outer circumference thereof,each disk defining at least one opening thereon for redirecting the windaxially through each of the disks; whereby, in use, the stator bladesredirect the wind tangentially to the rotor assembly and entirely withinthe enclosure formed by the stator blades before the wind is redirectedaxially through each of the disks.

PCT Application Publication No. 2010/003955, entitled “Wind turbineapparatus,” published 3 Feb. 2011 to Blafield et al. (“Blafield”).Blafield describes a wind turbine apparatus comprising a generator and asubstantially vertical shaft, the shaft being directly mounted to thegenerator for rotating the generator. At least one lightweight vanemember is also provided. The at least one vane member is attached to theshaft to provide a twisted self starting rotor unit. An electroniccontrol apparatus is provided for controlling the speed of rotation ofthe generator.

U.S. Patent Application Publication No. 2012/0099994, entitled“Vertical-axis wind rotor,” published 26 Apr. 2012 to Eguizabal(“Eguizabal”). Eguizabal describes a wind rotor with a vertical shaft,of the type which incorporates a pair of supports suitably fixed at theends of the shaft thereof, which supports form the support means for aplurality of blades aligned circumferentially about the shaft,comprising two types of blades with an identical or similar mainaerodynamic profile, vertically projected with advanced rotationaldisplacement and twisted and with a shortened chord in the oppositedirection, one blade configured for drag and another blade configuredfor lift, the chords of the blades being oriented at an angle, radially,uniformly, concentrically, and vertically at the base of the rotor, withthe leading edge outward, alternately and equidistantly arranged at thelower base thereof.

U.S. Pat. No. 8,232,664, entitled “Vertical axis wind turbine,” issued31 Jul. 2012 to Stroup et al. (“Stroup”). Stroup describes a verticalaxis wind turbine for generating electricity comprising a tower base; atower frame attached to the base; a vertically extending wind turbinemounted in the tower frame and having a central shaft and a plurality ofwind blades attached thereto, the shaft being attached to an electricgenerator for producing electricity therefrom upon rotation of theshaft; a plurality of diverter doors, each diverter door being movablyconnected to the tower frame adjacent the wind turbine, the plurality ofdiverter doors being movable to seal the wind turbine in a housingformed by the plurality of diverter doors when winds exceed apredetermined velocity; and a plurality of electric motors, one of theelectric motors being coupled to each of the diverter doors to variablyposition the coupled diverter door relative to each other diverter doorfor controlling air flow to the turbine, whereby a vertical standingwind turbine generates a controlled electrical output while controllingair flow to the wind turbine and being protected against storms by theindividual movement of each of a plurality of diverter doors.

U.S. Pat. No. 8,354,756, entitled “Vertical axis turbine to generatewind power,” issued 15 Jan. 2013 to Ellis (“Ellis”). Ellis describes anapparatus, comprising an axle extending along a center axis, and aplurality of cup shaped blades coupled to the axle around the centeraxis, each blade comprising a concave face having a parabolic concavityalong a plane parallel to the center axis, the parabolic concavityhaving a first focus and a first vertex; and a convex tail having anexterior surface that is parabolic along the plane parallel to thecenter axis, the exterior surface having a second focus coincident thefirst focus in the plane and a second vertex in the plane, wherein adistance between the first focus and the first vertex is less than adistance between the second focus and the second vertex.

U.S. Patent Application Publication No. 2013/0287570, entitled“Self-starting Savonius wind turbine,” published 31 Oct. 2013 to Gdovic(“Gdovic”). Gdovic describes a self-starting Savonius wind turbineincluding a frame, a rotor assembly that is rotatable about a centralaxis of rotation, and an energy utilizing device operably connected tothe rotor assembly. The rotor assembly has at least two rotors, eachrotor having at least two rotor blades. Rotation of the rotor assemblyis initiated by wind coming from any direction blowing on any one of theplurality of blades. The rotors are configured in a stacked orientationwith the blades fixed at a rotated angular position relative to oneanother to start rotation of the rotor assembly in variable windconditions.

U.S. Patent Application Publication No. 2014/0044535, entitled “Windturbines augmented with rotating diffusers,” published 13 Feb. 2014 toWood (“Wood I”). Wood I describes a diffuser-augmented wind turbineincluding a first diffuser ring arranged to form a turbine rotorcowling, the diffuser being fixed to and rotatable with the turbinerotor about the horizontal axis of the wind turbine. The first diffuserring may have one or more dynamic, aero-elastic, vortex entrainmentdevices attached to a trailing edge of the diffuser. The first diffuserring may include one or more slot gaps arranged within its body, eachslot gap creating a channel between the interior and exterior surfacesof the first diffuser ring.

U.S. Patent Application Publication No. 2014/0227092, entitled “Diffuseraugmented wind turbines,” published 14 Aug. 2014 to Wood (“Wood II”).Wood II describes a wind turbine diffuser with an expanded outlet areain which the diffuser outlet area is greater than its cross sectionalarea. The diffuser may be formed of one or more diffuser rings, at leastone of which may form a turbine cowling. Each diffuser ring may have aninlet area that is smaller than the outlet area of the directly upstreamring. The portion of an upstream ring outlet which is not occluded bythe downstream ring may form a diffuser outlet such that the totaloutlet area of the diffuser is larger than the cross-sectional area.U.S. Pat. No. 8,829,704, entitled “Wind turbine generator and motor,”issued 9 Sep. 2014 to Grigg (“Grigg”). Grigg describes a parallel andvertical axis turbine including a plurality of wing assemblies havingvertical pivot shafts extending between two vertically spaced endassemblies that are joined to a central driveshaft assembly. The wingassemblies are rotatable about their respective pivot axes from a driveposition in which they extend radially outwardly from the central axisand transverse to incident fluid flow to maximally capture fluid flowand rotate the turbine, to a glide position in which the wings extendtangentially to the direction of rotation and parallel to incident fluidflow to minimize drag.

U.S. Patent Application Publication No. 2014/0356180, entitled “Windturbine for facilitating laminar flow,” published 4 Dec. 2014 to Oelofse(“Oelofse”). Oelofse describes a circular-oriented laminar flowfacilitating turbine, comprising at least leading and trailingcircumferentially distributed foils, which rotate about an axis and aresized and spaced to facilitate a laminar flow between the foils, thefoils having leading edges at distances R1 and R2, respectively, fromthe axis, the foils having chords C1 and C2, respectively, and the foilsbeing spaced apart by a distance S, wherein R2 is within 10% of R1 andC2 is within 10% of C1, R1:C1 is between 2.9 and 3.5 inclusive, C1:S isat least 3:1 inclusive, and the leading foil has a high pressure portionand a low pressure portion, wherein at least 90% of the high pressureportion is curved in a manner that facilitates the laminar flow.

U.S. Patent Application Publication No. 2015/0063978, entitled “Windturbine,” published 5 Mar. 2015 to Poole (“Poole”). Poole describes avertical axis wind turbine system that converts wind energy intoelectrical or mechanical energy, comprising at least one turbine rotorwith a plurality of blades for receiving head-on wind generated airflow,at least some of the blades moving in a downstream wind direction andsome of the blades moving in a return upwind direction as the rotorrotates; a rotor support structure mountable to a base or support forholding the at least one rotor in the wind generated airflow; and windshield means mountable upwind of at least a portion of the rotor toprotect the return blades from head-on wind airflow.

U.S. Patent Application Publication No. 2015/0086366, entitled “Windturbine blade and blade hub,” published 26 Mar. 2015 to Barnes et al.(“Barnes”). Barnes describes a Darrieus-type vertical axis wind turbinecomprising a vertical tower supported for rotation, and one or moreblades each connected to the tower causing rotation in response to windenergy therewith, wherein each blade has an upper root end connected tothe top of the tower by a separable blade hub and a lower root endconnected to the bottom of the tower by a separable blade hub.

U.S. Patent Application Publication No. 2015/0152840, entitled“Dual-turbine wind power station placed on a vertical axis,” published 4Jun. 2015 to Varga et al. (“Varga”). Varga describes a dual-turbine windpower station arranged on a vertical axis, comprising a machine housingconstructed over a solid base; an internal rotor comprising one or moreblades; an internal shaft having a lower set of bearings at a point onits lower end and an upper set of bearings at a point on its upper end,both of which provide for rotational motion of the shaft about thevertical axis of the internal shaft, the lower end of which is connectedto a first electric energy-producing electrical machine either directly,or with the aid of a first transmission device; an external rotor whichrotates in a direction opposite to that of the internal rotor comprisingone or more blades, an external shaft which rotates about the verticalaxis it shares with the internal rotor, the external shaft having alower set of bearings at a point on its lower end and an upper set ofbearings at a point on its upper end, both of which provide forrotational motion of the shaft about the vertical axis of the externalshaft, wherein the lower shaft end of the internal rotor is placed intothe lower shaft end of the external rotor and the lower end of theexternal shaft is connected to a second electric energy-producingelectrical machine either directly, or via a second transmission device;

and an oval support structure comprising a grid-like shell thatsurrounds the internal rotor and external rotor.

As may be understood by those of ordinary skill in the art, certaincomponents or features of the foregoing references may be incorporatedand used in embodiments of the present disclosure. By way ofnon-limiting example, particular shapes or arrangements of blades,materials used to construct devices, or device sizes as disclosed in theprior art may be incorporated into embodiments of the presentdisclosure, and such uses are within the scope of this disclosure.

In various embodiments of the present invention, the blade design hasboth drag and lift characteristics. In some embodiments, an open rotordesign allows for the lift feature to be taken advantage of.Specifically, an open rotor design permits air to flow over the bladesto fully develop the lift and does not limit the flow to adjoiningblades.

In various embodiments of the present invention, the stator skirt designamplifies and accelerates the wind speed into the rotor. This isimportant because the power output of a wind turbine scales with thecube of the wind speed, e.g. a twofold increase in the wind speedresults in an eightfold increase in available power. The VAWTs of thepresent invention can rotate even at very low wind speeds as a result ofthe wind speed amplification provided by the stator skirt.

In various embodiments of the present invention, stator fins direct thewind in the direction of blade rotation and have a major impact on theoverall torque efficiency.

In various embodiments of the present invention, an open frame designallows the entire rotor-stator system to receive wind energy from anydirection. Wind varies greatly in direction and velocity on a continuousbasis, and also exhibits rolling and swirling vortices. The VAWTs of thepresent invention can respond instantaneously to any change in winddirection or velocity.

As used herein, “at least one,” “one or more,” and “and/or” areopen-ended expressions that are both conjunctive and disjunctive inoperation. For example, each of the expressions “at least one of A, B,and C,” “at least one of A, B, or C,” “one or more of A, B, and C,” “oneor more of A, B, or C,” and “A, B, and/or C” means A alone, B alone, Calone, A and B together, A and C together, B and C together, or A, B,and C together.

It is to be noted that the term “a” or “an” entity refers to one or moreof that entity. As such, the terms “a” (or “an”), “one or more,” and “atleast one” can be used interchangeably herein. It is also to be notedthat the terms “comprising,” “including,” and “having” can be usedinterchangeably.

The embodiments and configurations described herein are neither completenor exhaustive. As will be appreciated, other embodiments of theinvention are possible utilizing, alone or in combination, one or moreof the features set forth above or described in detail below.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A and 1B are perspective and top cross-sectional views,respectively, of a basic vertical axis wind turbine according toembodiments of the present disclosure;

FIG. 2 is a top cross-sectional view of a vertical axis wind turbinehaving blades of constant cross-sectional width, according toembodiments of the present disclosure;

FIG. 3 is a top cross-sectional view of a vertical axis wind turbinehaving six stator fins, according to embodiments of the presentdisclosure;

FIG. 4 is a top cross-sectional view of a vertical axis wind turbinehaving a stator skirt angle of 60°, according to embodiments of thepresent disclosure; FIG. 5 is a top cross-sectional view of a verticalaxis wind turbine having a unitary rotor, according to embodiments ofthe present disclosure;

FIG. 6 is a top cross-sectional view of a vertical axis wind turbinehaving solid rotor plates devoid of holes or gaps, according toembodiments of the present disclosure;

FIG. 7 is an isometric view of a vertical axis wind turbine having anamplifier skirt, according to embodiments of the present disclosure;

FIG. 8 is a top cross-sectional view of a vertical axis wind turbinehaving rotor blades with diameters larger than a radius of a rotorplate, according to embodiments of the present disclosure;

FIGS. 9A and 9B are top cross-sectional and isometric views,respectively, of a vertical axis wind turbine having an amplifier skirtand enlarged stator fins, according to embodiments of the presentdisclosure;

FIGS. 10A, 10B, and 10C are isometric, front, and top cross-sectionalviews, respectively, of a vertical axis wind turbine having parabolicstator and amplifier skirts, according to embodiments of the presentdisclosure;

FIGS. 11A and 11B are each computer-generated views of air flow throughthe vertical axis wind turbine illustrated in FIGS. 1A and 1B;

FIGS. 12A, 12B, and 12C are each computer-generated views of air flowthrough the vertical axis wind turbine illustrated in FIG. 7;

FIGS. 13A, 13B, and 13C are each computer-generated views of air flowthrough the vertical axis wind turbine illustrated in FIGS. 9A and 9B;and

FIG. 14 is a bar graph showing the mechanical efficiency of verticalaxis wind turbines according to various embodiments of the presentdisclosure.

DETAILED DESCRIPTION OF THE INVENTION

Referring now to FIG. 1A, a basic vertical axis wind turbine isillustrated. As illustrated in FIG. 1A, vertical axis wind turbinesaccording to the present disclosure comprise five parts: a stator skirt110, at least one stator fin 120, at least one rotor plate 130, at leastone rotor blade 140, and a top frame 150. Additional parts may be, butneed not be, present to fall within the scope of the present disclosure.The rotor blades 140 turn a shaft and are attached to the rotor plates130 at the top, the bottom, or both of the rotor blades 140. The statorskirt 110 supports the rotor plates 130 and, as illustrated in FIG. 1A,is rotationally symmetric and comprises trapezoidal panels, with eachtrapezoidal panel forming an angle with respect to a horizontal axis.Thus, the stator skirt 110 has a horizontal cross-section of a regularpolygon with a number of sides equal to the number of trapezoidalpanels. The stator fins 120 are attached at their bottoms to the statorskirt 110. Each stator fin 120 comprises a fin flip, which is disposedat an angle to the longitudinal axis of the stator fin 120 and isadapted to compress wind and direct the wind to the rotor blades 140 ina predetermined direction. The top frame 150 is attached to the tops ofthe stator fins 120 and is provided to maintain rigidity and structuralintegrity of the stator fins 120 and the vertical axis wind turbine as awhole.

Referring now to FIG. 1B, various design features of the vertical axiswind turbine are illustrated. In this embodiment, three semiellipticalcrescent-shaped rotor blades 140 are provided, each forming an angle of120° relative to each of the other rotor blades 140; those of ordinaryskill in the art will understand that other numbers, arrangements, andshapes of rotor blades 140 may be suitable for particular applications.In this embodiment, three stator fins 120 spaced 120° apart areprovided; those of ordinary skill in the art will understand that othernumbers and arrangements of stator fins 120 may be suitable forparticular applications. In this embodiment, each fin flip forms anangle of 45° relative to the longitudinal axis of the stator fin 120 andis two inches in length; those of ordinary skill in the art willunderstand that other angles and lengths of fin flips may be suitablefor particular applications. In this embodiment, the stator skirt 110comprises six trapezoidal panels and thus has a horizontal cross-sectionof a regular hexagon, with each trapezoidal panel forming an angle of36° relative to a horizontal axis; those of ordinary skill in the artwill understand that other numbers and angles of trapezoidal panels, andthus other shapes of stator skirt 110, may be suitable for particularapplications.

Referring now to FIG. 2, another embodiment of a vertical axis windturbine is illustrated. This embodiment is similar to the embodimentillustrated in FIG. 1B, except that the rotor blades 140 have constantcross-sectional width, as opposed to the crescent-shaped blades 140 ofFIG. 1B.

Referring now to FIG. 3, another embodiment of a vertical axis windturbine is illustrated. This embodiment is similar to the embodimentillustrated in FIG. 1B, except that the turbine is provided with sixstator fins 120, as opposed to the three stator fins 120 of FIG. 1B.Referring now to FIG. 4, another embodiment of a vertical axis windturbine is illustrated.

This embodiment is similar to the embodiment illustrated in FIG. 1B,except that the trapezoidal panels of the stator skirt 110 form an angleof 60° relative to a horizontal axis, as opposed to the 36° angle ofFIG. 1B.

Referring now to FIG. 5, another embodiment of a vertical axis windturbine is illustrated. This embodiment is similar to the embodimentillustrated in FIG. 1B, except that the rotor blades 140 areinterconnected to form a unitary rotor, as opposed to FIG. 1B, in whicheach rotor blade 140 is a separate component, attached to at least onerotor plate 130 but not to the other rotor blades 140.

Referring now to FIG. 6, another embodiment of a vertical axis windturbine is illustrated. This embodiment is similar to the embodimentillustrated in FIG. 1B, except that the rotor plates 130 are solid anddevoid of holes or gaps, as opposed to FIG. 1B, in which holes arepresent in the rotor plates 130.

Referring now to FIG. 7, another embodiment of a vertical axis windturbine is illustrated. This embodiment is similar to the embodimentillustrated in FIG. 1B, except that the turbine is provided with anamplifier skirt 160, disposed on top of the vertical axis wind turbineand attached to the top frame 150. As illustrated in FIG. 7, theamplifier skirt 160 may be, but need not be, a “mirror image” of thestator skirt 110. The amplifier skirt 160 captures and amplifies thewind and directs it into the uppermost of two sets of vertically stackedrotor blades 140.

Referring now to FIG. 8, another embodiment of a vertical axis windturbine is illustrated. This embodiment is similar to the embodimentillustrated in FIG. 1B, except that the rotor blades 140 have a diameterthat is larger than a radius of the rotor plate 130, as opposed to theblades 140 of smaller diameter in FIG. 1B. Thus, in the embodimentillustrated in FIG. 8, the rotor blades 140 “overlap” near the shaft.

Referring now to FIG. 9A, another embodiment of a vertical axis windturbine is illustrated. In this embodiment, the vertical axis windturbine is provided with substantially enlarged stator fins 120 and finflips, each stator fin 120 now having a longitudinal axis that runs mostof the way from an outer edge of the rotor plate 130 to an outer edge ofthe stator skirt 110. The enlarged stator fins 120 and fin flips funneland direct a significantly increased volume of incoming wind into therotor blades 140 as compared to smaller stator fins 120, for example asillustrated in FIG. 1B. Referring now to FIG. 9B, an isometric view ofthe embodiment of FIG. 9A is illustrated. The embodiment also comprisesan amplifier skirt 160 similar to that illustrated in FIG. 7, disposedon top of the vertical axis wind turbine and attached to the top frame150. As illustrated in FIG. 9B, the amplifier skirt 160 may be, but neednot be, a “mirror image” of the stator skirt 110. The amplifier skirt160 captures and amplifies the wind and directs it into the rotor blades140.

The angle α between a horizontal axis and the surface of the statorskirt 110 and/or amplifier skirt 160 may be selected to provide adesired wind shaping profile. By way of first non-limiting example, theangle α may be less than about 90°, less than about 85°, less than about80°, less than about 75°, less than about 70°, less than about 65°, lessthan about 60°, less than about 55°, less than about 50°, less thanabout 45°, less than about 40°, less than about 35°, less than about30°, less than about 25°, less than about 20°, less than about 15°, lessthan about 10°, or less than about 5°, or alternatively less than aboutany whole number of degrees between about 1 and about 90. By way ofsecond non-limiting example, the angle α may be more than about 0°, morethan about 5°, more than about 10°, more than about 15°, more than about20°, more than about 25°, more than about 30°, more than about 35°, morethan about 40°, more than about 45°, more than about 50°, more thanabout 55°, more than about 60°, more than about 65°, more than about70°, more than about 75°, more than about 80°, or more than about 85°,or alternatively more than about any whole number of degrees betweenabout 0 and about 89. It is to be expressly understood that the angle αof the stator skirt 110 and the angle α of the amplifier skirt 160 maybe the same or different.

Referring now to FIGS. 10A and 10B, another embodiment of a verticalaxis wind turbine is illustrated. As illustrated in FIGS. 10A and 10B,vertical axis wind turbines according to the present disclosure compriseat least three parts: a stator skirt 210, at least one stator fin 220,and at least one rotor blade 240. Additional parts, such as a rotorplate (not illustrated), may be, but need not be, present to fall withinthe scope of the present disclosure. The rotor blades 240 turn a shaft,and may in some embodiments be attached to rotor plates (if present) atthe top, the bottom, or both of the rotor blades 240. The stator skirt210, as illustrated in FIGS. 10A and 10B, is rotationally symmetric andcomprises a paraboloid, typically an elliptical paraboloid, such that atleast a portion of a wind-facing surface of the stator skirt 210 has agenerally parabolic shape. The stator skirt 210 also comprises asubstantially planar base for stability when placed on the ground oranother horizontal support. In some embodiments, as illustrated in FIGS.10A and 10B, the surface of the stator skirt 210 may comprise twoportions: an approximately conical lower portion (i.e. where the slopeof the surface relative to a horizontal axis is approximately constant)and an approximately parabolic upper portion (i.e. where the slope ofthe surface relative to a horizontal axis generally decreases withincreasing vertical distance from the substantially planar base, andmay, but need not, be approximately zero at an apex or vertex of thestator skirt 210). Importantly, the stator skirt 210 typically has ahorizontal cross-section not of a polygon but rather of an ellipse, andin many embodiments a circle. The stator fins 220 are attached at theirbottoms to the stator skirt 210. Each stator fin 220 comprises a finflip, which is disposed at an angle to the longitudinal axis of thestator fin 220 and is adapted to compress wind and direct the wind tothe rotor blades 240 in a predetermined direction. In some embodiments,a top frame (not illustrated) may be provided, and may be attached tothe tops of the stator fins 220 to maintain rigidity and structuralintegrity of the stator fins 220 and the vertical axis wind turbine as awhole.

As illustrated in FIGS. 10A and 10B, the vertical axis wind turbine alsocomprises an amplifier skirt 260, disposed on top of the vertical axiswind turbine and attached to the tops of stator fins 220 (or, in someembodiments, a top frame to which the stator fins 220 may in turn beattached). The amplifier skirt 260 captures and amplifies the wind anddirects it into the rotor blades 240.

As further illustrated in FIGS. 10A and 10B, the amplifier skirt 260 maybe, but need not, be, a “mirror image” of the stator skirt 210. Theamplifier skirt 260 generally, like the stator skirt 210, isrotationally symmetric and comprises a paraboloid, typically anelliptical paraboloid, in which at least a portion of a wind-facingsurface of the amplifier skirt 260 has a generally parabolic shape,extending downwardly from a top portion to form an angle with respect toa horizontal axis. In some embodiments, as illustrated in FIGS. 10A and10B, the surface of the amplifier skirt 260 may comprise at least twoportions: an approximately conical upper portion (i.e. where the slopeof the surface relative to a horizontal axis is approximately constant)and an approximately parabolic lower portion (i.e. where the slope ofthe surface relative to a horizontal axis generally decreases withincreasing vertical distance from the approximately conical portion, andmay, but need not, be approximately zero at an apex or vertex of theamplifier skirt 260). Unlike the stator skirt 210, whose base mustgenerally be substantially planar for stability, the amplifier skirt 260may additionally have a curved, arcuate, or parabolic top portion, asillustrated in FIGS. 10A and 10B; however, in some applications (e.g.where it is intended to vertically stack multiple vertical axis windturbines, one atop another), it may be desirable for the amplifier skirt260 to have a substantially planar top portion.

Referring now to FIG. 10C, various design features of the vertical axiswind turbine are illustrated. In this embodiment, three arcuate rotorblades 240 are provided, each forming an angle of about 120° relative toeach of the other rotor blades 240; those of ordinary skill in the artwill understand that other numbers, arrangements, and shapes of rotorblades 240 may be suitable for particular applications. In thisembodiment, three stator fins 220 spaced about 120° apart are provided;those of ordinary skill in the art will understand that other numbersand arrangements of stator fins 220 may be suitable for particularapplications. In this embodiment, each fin flip 225 forms an angle ofabout 45° relative to the longitudinal axis of the stator fin 220; thoseof ordinary skill in the art will understand that other angles andlengths of fin flips may be suitable for particular applications. Inthis embodiment, the stator skirt 210 comprises a circular paraboloid,i.e. has a circular horizontal cross-section; those of ordinary skill inthe art will understand that other shapes, most typically ellipticalshapes, of the horizontal cross-section of the stator skirt 210 may besuitable for particular applications.

The angle α between a horizontal axis and the surface of the statorskirt 210 and/or amplifier skirt 260, as measured by an average or atany point of the stator skirt 210 and/or the top of the amplifier skirt260, may be selected to provide a desired wind shaping profile. By wayof first non-limiting example, the angle α may be less than about 90°,less than about 85°, less than about 80°, less than about 75°, less thanabout 70°, less than about 65°, less than about 60°, less than about55°, less than about 50°, less than about 45°, less than about 40°, lessthan about 35°, less than about 30°, less than about 25°, less thanabout 20°, less than about 15°, less than about 10°, or less than about5°, or alternatively less than about any whole number of degrees betweenabout 1 and about 90. By way of second non-limiting example, the angle αmay be more than about 0°, more than about 5°, more than about 10°, morethan about 15°, more than about 20°, more than about 25°, more thanabout 30°, more than about 35°, more than about 40°, more than about45°, more than about 50°, more than about 55°, more than about 60°, morethan about 65°, more than about 70°, more than about 75°, more thanabout 80°, or more than about 85°, or alternatively more than about anywhole number of degrees between about 0 and about 89. As describedabove, the shape of the surface of the stator skirt 210 and/or amplifierskirt 260 may be entirely parabolic (i.e. the angle α decreasescontinuously from the base of the stator skirt 210 and/or top of theamplifier skirt 260, e.g. to about zero at an apex or vertex of thestator skirt 210 and/or amplifier skirt 260), or may comprise both aparabolic portion and a conical portion (i.e. the angle α issubstantially constant). It is to be expressly understood that the angleα of the stator skirt 210 and the angle α of the amplifier skirt 260 maybe the same or different.

One advantage of the present invention lies in its usefulness to shapethe arcuate rotor blades 240 to correspond to, interface with, and/ormatch the shape of the stator skirt 210 and/or amplifier skirt 260 toprovide a desired airflow pattern. By way of first non-limiting example,a center or terminal point of one or more rotor blades 240, when therotor blade 240 is in a selected rotational position, may coincide witha center of curvature of the stator skirt 210 and/or amplifier skirt 260or a portion thereof. By way of second non-limiting example, a radius ofcurvature of one or more rotor blades 240 may be the same as, or have aselected ratio to, a radius of curvature of the stator skirt 210 and/oramplifier skirt 260 or a portion thereof.

In some embodiments, vertical axis wind turbines of the presentinvention may include rotor blades 240 that are modular, i.e. that canbe individually repaired or replaced without disassembly or modificationof other rotor blades 240 or any other part of the vertical axis windturbine. Particularly, in the practice of the present invention, it maybe possible to add, remove, or replace one or more rotor blades 240without disturbing the other rotor blades 240, thus reducing downtime ofthe turbine as a whole, and potentially even allowing the turbine tooperate with less than a full complement of rotor blades 240 while oneor more of the blades are replaced, repaired, and/or refurbished. Themodularity of rotor blades 240 may also make assembly lesstime-consuming and challenging, and/or may allow for the ability toadapt the turbine to a particular environment of use or modify the windturbine after initial installation.

Another advantage of the present invention is that, unlike many verticalaxis wind turbines of the prior art, a ratio of the turbine's height toits diameter or width may be kept relatively low.

A low height-to-width ratio provides several advantages, including butnot limited to improved performance and improved ability to stackturbines atop each other. By way of non-limiting example,height-to-width ratios of turbines of the present invention may be lessthan about 3.0, less than about 2.9, less than about 2.8, less thanabout 2.7, less than about 2.6, less than about 2.5, less than about2.4, less than about 2.3, less than about 2.2, less than about 2.1, lessthan about 2.0, less than about 1.9, less than about 1.8, less thanabout 1.7, less than about 1.6, less than about 1.5, less than about1.4, less than about 1.3, less than about 1.2, less than about 1.1, lessthan about 1.0, less than about 0.9, less than about 0.8, less thanabout 0.7, less than about 0.6, less than about 0.5, less than about0.4, less than about 0.3, less than about 0.2, or less than about 0.1,or alternatively may fall within a range of at least about any tenth ofa whole number between about 0.1 and about 3.0 and no more than aboutany other tenth of a whole number between about 0.1 and about 3.0.

Another advantage of the present invention is that, unlike many verticalaxis wind turbines of the prior art, the embodiment illustrated in FIGS.10A through 10C presents no corners or sharp edges in the path ofoncoming wind. Instead, all wind-facing surfaces of the turbine of FIGS.10A through 10C are arcuate, parabolic, or otherwise free of sharpangles. This feature of the present invention may provide severalimportant benefits. By way of first non-limiting example, corners orsharp edges in the path of air into the turbine may impede the flow ofair to the rotor blades 240, create discontinuities or other undesirableeffects in the pattern of air flow, or otherwise diminish theeffectiveness of the turbine in efficiently capturing wind energy; byproviding wind-facing surfaces free of sharp angles, the embodimentillustrated in FIGS. 10A through 10C may thus have an improved airflowpattern and/or improved efficiency. By way of second non-limitingexample, stresses or other forces exerted on the turbine by incoming airmay be exacerbated by and/or focused upon corners or sharp edges, thusmaking the turbine more susceptible to mechanical damage or failure ator near such corners or sharp edges; by providing wind-facing surfacesfree of sharp angles, the embodiment illustrated in FIGS. 10A through10C may thus have improved structural integrity and/or an extendeduseful life.

Another advantage of the present invention is that, due to the improvedmechanical resilience and structural integrity of the vertical axis windturbine and its components, lighter materials, i.e. materials having alower density and/or a higher strength-to-weight ratio, may be used toconstruct any one or more of the stator skirt 110/210, the stator fins120/220, the rotor plate 130, the rotor blades 140/240, the top frame150, the amplifier skirt 160/260, and/or any other parts or componentsof the vertical axis wind turbine. By way of non-limiting example, anyone or more of these and/or other components may comprise a materialselected from the group consisting of fiberglass, lightweight wood (e.g.balsa wood), aluminum, and a solid foam.

Referring now to FIGS. 11A and 11B, air flow through the embodiment ofFIGS. 1A and 1B is illustrated.

Referring now to FIGS. 12A, 12B, and 12C, air flow through theembodiment of FIG. 7 is illustrated.

Referring now to FIGS. 13A, 13B, and 13C, air flow through theembodiment of FIGS. 9A and 9B is illustrated.

Referring now to FIG. 14, the mechanical efficiency of variousembodiments is illustrated. Specifically, the bar labeled R34 refers tothe embodiment illustrated in FIG. 2; the bar labeled R33 refers to theembodiment illustrated in FIGS. 1A and 1B; the bar labeled R36 refers tothe embodiment illustrated in FIG. 3; the bar labeled R38 refers to theembodiment illustrated in FIG. 5; the bar labeled R39 refers to theembodiment illustrated in FIG. 6; the bar labeled R42 refers to theembodiment illustrated in FIG. 8; the bar labeled R40 refers to theembodiment illustrated in FIG. 7; and the bar labeled R50 refers to theembodiment illustrated in FIGS. 9A and 9B. The bar labeled R45 refers toan embodiment not specifically illustrated in the Drawings but withinthe scope of this disclosure. These efficiency values were calculatedbased on computational fluid dynamics (CFD) analyses which simulatedwind flow and wind loading on the various features of the severalembodiments. As FIG. 14 illustrates, the embodiment illustrated in FIG.7 and the embodiment illustrated in FIGS. 9A and 9B are most efficient.One of ordinary skill in the art, however, will recognize that variousother embodiments and features of embodiments may be suitable forparticular applications.

Vertical axis wind turbines have been proposed to address the problem inwind direction. In vertical axis wind turbines a rotor assembly rotatestypically on bearing assemblies affixed to a rotor shaft and supportedby a base. See, e.g., U.S. Pat. Nos. 1,697,574 and 1,766,765 to Savoniusand U.S. Pat. No. 1,835,018 to Darrieus. Prior art designs, however,suffer from poor efficiency and starting problems, have vertical rotorsthat do not rotate fast enough, have insufficient rotor tip velocities,and complex and expensive rotor blade designs. Conventional verticalwind turbines, despite being capable of operating from wind coming fromany direction, have not been as widely used in generation of energy ashave horizontal turbines, due to one or more of the above referencedproblems, The present invention, however, addresses such deficienciesand thus provides a superior device and method for generating electricalenergy.

Certain embodiments of the present invention include a wind turbineapparatus comprising a generator, a substantially vertical shaft, theshaft being adapted to be directly mounted to the generator for rotatingthe generator, a plurality of shaped blades associated with the shaft,and in some embodiments, an electronic control apparatus for controllingthe speed of rotation of the generator by controlling loading of thegenerator. In certain embodiments, a permanent magnet synchronousgenerator is employed where at least one permanent magnet comprises atleast one rare earth metal. In other embodiments, at least one of thestators, blades, and base and top wind deflector panels (e.g. when ahexagonal construct is used) are adjustable in terms of one of: size,length, extension (such as by having telescoping elements adjustable inview of wind conditions), angle, shape, ribbing, canting, andtemperature (e.g. so as to melt ice or snow thereon). In variousembodiments, a control apparatus or controller for controlling operationof at least one vertical wind turbine (and in certain embodiments, twoor more stacked turbines) includes a processor to optimize rotationbased on wind speed and power output, tip speed, and/or positioning ofthe rotor and the stator of the generator such that a predeterminedrelation between the wind speed and tip speed and/or power output ismaintained.

The controller may, additionally or alternatively, control other aspectsor parameters of the vertical axis wind turbine or systems comprisingvertical axis wind turbines. By way of first non-limiting example, thecontroller may be operable to control mechanical parameters of thegenerator; particularly, where the generator is an alternator (i.e. agenerator producing alternating current), the controller may be operableto control the number of poles, rotational speed, and/or frequency ofthe alternator. By way of second non-limiting example, the controllermay be operable to control the output voltage of the electricalgenerator, e.g. by reconfiguring a voltage regulator. By way of thirdnon-limiting example, the vertical axis wind turbine (or systemcomprising a vertical axis wind turbine) may comprise, in addition tothe controller, a mechanical and/or electronic braking mechanism foreither the rotor blades 140/240, the generator shaft, or both, and thecontroller may be operable to apply the braking mechanism to slow therotation of the rotor blades 140/240, the generator shaft, or both whenthe rotational speed exceeds a predetermined value.

Various embodiments are adapted to be ground secured units, while otherembodiments provide wind turbine devices adapted for positioning on aroof, pole, scaffold or on a mast, and preferably include atelecommunications or other remote control functionalities such thatremote control of the units can be achieved to maximize efficiencies andpower output. Still other embodiments provide for protective shields tobe put in place, preferably via remote control, such that the units areprotected from certain environmental conditions when desired, such as inextremely high winds, storms, etc. The units can be made from anysuitable material, but in certain embodiments, they comprise a majorityof plastic or composite portions to reduce weight, to facilitatemanufacture and to promote use when weight characteristics areparamount. Thus many embodiments include those made form from at leastone of plastic material, composite material, laminate material,fiberglass and aluminum.

The power generation system may comprise a local grid, means forconverting from AC to DC voltage between the at least one wind turbineapparatus and the local grid, a local energy storage connected to thelocal grid, at least one further local energy production apparatus, anda connection to another grid. Directing the output of such units to astorage facility or to charge batteries is also contemplated.

Similarly, the provision of photovoltaic panels as part of the windturbine constructs is rendered possible due to the expansive panels ofthe base and top portions (in certain embodiments), including theuppermost portion of the units that will be exposed to sunlight, thusfacilitating energizing of the units with the assistance of solarpowered systems. By way of first non-limiting example, a photovoltaicpanel may be placed on a suitable portion of the surface of theamplifier skirt 160/260. By way of second non-limiting example, theamplifier skirt 160/260 may itself be a photovoltaic panel, i.e. mayperform the dual function of shaping incoming wind into the rotor blades140/240 while simultaneously producing solar energy. In certainembodiments in which vertical axis wind turbines of the inventioninclude, or are integrated with, photovoltaic systems, a controller maybe operable to synchronize alternating current waveforms of thewind-generated current and the solar-generated current, and may inembodiments be enabled to synchronize the total electrical output of thevertical axis wind turbine system with an electrical grid or network towhich the vertical axis wind turbine system is interconnected.

Embodiments of vertical axis wind turbines according to the presentinvention may comprise, or be configured to work with, a gearbox, whichconverts the rotation of the rotor blades 140/240 into a rotation(usually at a faster rotational speed) of an electrical generator toproduce electricity. However, in many embodiments, it is possible andmay be desirable for a “direct-drive” system to be provided, in whichthe shaft turned by the rotor blades 140/240 is directly interconnectedto an electrical generator, without an intermediate gearbox, such thatthe generator spins at the same speed as rotor blades 140/240; typically(but not always), the slower rotational speed of the generator iscompensated for by increasing the diameter of the generator's rotor toallow for the inclusion of more magnets to create the required frequencyand power. Such “direct-drive” vertical axis wind turbines may bepreferred over generation systems comprising a gearbox for variousreasons, including, by way of non-limiting example, increasedefficiency, reduced noise, longer lifetime, higher torque at lowrotational speeds, faster and more precise positioning, drive stiffness,and avoidance of certain mechanical issues to which gearboxes may beparticularly susceptible (e.g. accumulated fatigue torque loading,reliability issues, maintenance costs, etc.). Thus, it is to beexpressly understood that the scope of the present invention includesboth vertical axis wind turbine systems comprising (or adapted tointerface with) a generator system comprising a gearbox, and verticalaxis wind turbine systems comprising (or adapted to interface with) adirect-drive generator system (e.g. a permanent magnet synchronousgenerator). These and other embodiments may also provide vertical axiswind turbine systems according to the present invention having fewermoving parts than those of the prior art, further reducing maintenanceneeds and costs and improving the useful life of the turbine system.

The invention illustratively disclosed herein suitably may be practicedin the absence of any element which is not specifically disclosedherein. It is apparent to those skilled in the art, however, that manychanges, variations, modifications, other uses, and applications of theinvention are possible, and also changes, variations, modifications,other uses, and applications which do not depart from the spirit andscope of the invention are deemed to be covered by the invention, whichis limited only by the claims which follow. The foregoing discussion ofthe invention has been presented for purposes of illustration anddescription. The foregoing is not intended to limit the invention to theform or forms disclosed herein. In the foregoing Detailed Description ofCertain Embodiments of the Invention, for example, various features ofthe invention are grouped together in one or more embodiments for thepurpose of streamlining the disclosure. The features of the embodimentsof the invention may be combined in alternate embodiments other thanthose discussed above. This method of disclosure is not to beinterpreted as reflecting an intention that the claimed inventionrequires more features than are expressly recited in each claim. Rather,as the following claims reflect, inventive aspects lie in less than allfeatures of a single foregoing disclosed embodiment. Thus, the followingclaims are hereby incorporated into this Detailed Description of CertainEmbodiments of the Invention, with each claim standing on its own as aseparate preferred embodiment of the invention.

Moreover, though the description of the invention has includeddescription of one or more embodiments and certain variations andmodifications, other variations, combinations, and modifications arewithin the scope of the invention, e.g. as may be within the skill andknowledge of those in the art, after understanding the presentdisclosure. It is intended to obtain rights which include alternativeembodiments to the extent permitted, including alternate,interchangeable, and/or equivalent structures, functions, ranges, orsteps to those claimed, whether or not such alternate, interchangeable,and/or equivalent structures, functions, ranges, or steps are disclosedherein, and without intending to publicly dedicate any patentablesubject matter.

1. A vertical axis wind turbine, comprising: at least one rotor blade,adapted to turn a shaft; a rotationally symmetric stator skirt, whereinat least a portion of a wind-facing surface of the stator skirt isparabolic, and wherein the stator skirt has a horizontal cross-sectionof an ellipse; and at least one stator fin, each stator fin beingattached at a bottom of the stator fin to the stator skirt andcomprising a fin flip, the fin flip being disposed at an angle of βrelative to a longitudinal axis of the stator fin and adapted tocompress wind and direct the wind to the rotor blades in a predetermineddirection.
 2. The vertical axis wind turbine of claim 1, wherein thepredetermined direction is counterclockwise.
 3. The vertical axis windturbine of claim 1, wherein the at least one rotor blade comprises threerotor blades.
 4. The vertical axis wind turbine of claim 1, wherein atleast one of a leading vertical face and a trailing vertical face ofeach rotor blade is arcuate or parabolic.
 5. The vertical axis windturbine of claim 1, wherein the at least one stator fin comprises threestator fins.
 6. The vertical axis wind turbine of claim 1, wherein thewind-facing surface of the stator skirt comprises a lower conicalportion and an upper parabolic portion.
 7. The vertical axis windturbine of claim 1, wherein an angle α between the wind-facing surfaceof the stator skirt and a horizontal axis, as measured by an average orat any point of the stator skirt, is less than about 45° or more thanabout 55°.
 8. The vertical axis wind turbine of claim 7, wherein α isbetween about 35° and about 40° or between about 55° and about 65°. 9.The vertical axis wind turbine of claim 1, wherein the ellipse is acircle.
 10. The vertical axis wind turbine of claim 1, having aheight-to-width ratio of between about 0.1 and about 3.0.
 11. A verticalaxis wind turbine, comprising: at least one rotor blade, adapted to turna shaft; a rotationally symmetric stator skirt, wherein at least aportion of a wind-facing surface of the stator skirt is parabolic, andwherein the stator skirt has a horizontal cross-section of an ellipse; arotationally symmetric amplifier skirt, wherein at least a portion of awind-facing surface of the amplifier skirt is parabolic, and wherein theamplifier skirt has a horizontal cross-section of an ellipse; and atleast one stator fin, each stator fin being attached at a bottom of thestator fin to the stator skirt and comprising a fin flip, the fin flipbeing disposed at an angle of β relative to a longitudinal axis of thestator fin and adapted to compress wind and direct the wind to the rotorblades in a predetermined direction.
 12. The vertical axis wind turbineof claim 11, wherein at least one of a leading vertical face and atrailing vertical face of each rotor blade is arcuate or parabolic. 13.The vertical axis wind turbine of claim 11, wherein the wind-facingsurface of the amplifier skirt comprises an upper conical section and alower parabolic section.
 14. The vertical axis wind turbine of claim 11,wherein at least one of the ellipse of the stator skirt and the ellipseof the amplifier skirt is a circle.
 15. The vertical axis wind turbineof claim 11, having a height-to-width ratio of between about 0.1 andabout 3.0.
 16. A vertical axis wind turbine, comprising: at least onerotor blade, adapted to turn a shaft; at least one rotor plate attachedto the at least one rotor blade at one or both of a top and a bottom ofthe at least one rotor blade; a rotationally symmetric stator skirt,supporting the at least one rotor plate and comprising N identicaltrapezoidal panels, each trapezoidal panel forming an angle α withrespect to a horizontal axis, the stator skirt having a horizontalcross-section of a regular polygon having N sides; at least one statorfin, each stator fin being attached at a bottom of the stator fin to thestator skirt and comprising a fin flip, the fin flip being disposed atan angle of β relative to a longitudinal axis of the stator fin andadapted to compress wind and direct the wind to the rotor blades in apredetermined direction; and a top frame, attached to a top of eachstator fin, wherein α is less than about 45° or more than about 55°. 17.The vertical axis wind turbine of claim 16, wherein the predetermineddirection is counterclockwise.
 18. The vertical axis wind turbine ofclaim 16, wherein the at least one rotor blade comprises three rotorblades.
 19. The vertical axis wind turbine of claim 16, wherein each ofa leading vertical face and a trailing vertical face of each rotor bladeis semielliptical.
 20. The vertical axis wind turbine of claim 16,wherein α is one of (i) more than about 12° and less than about 45° and(ii) more than about 55° and less than about 80°.